Bacteria and fungi associated with field- or nursery-grown coffee (Coffea arabica) plants can contaminate coffee explants in vitro. Out of 9 bacterial isolates obtained from such plants, 4 belonged to the genus Bacillus and 5 to the genus Erwinia, while all the fungal isolates were Rhizoctonia sp. Out of 35 antibacterial agents tested, only nalidixic acid, oxylynic acid, cefotaxin and sulfazotin inhibited the growth of all the bacterial isolates. All fungal isolates were inhibited by benomyl. The effect of these compounds on the development of coffee explants could not be determined because of high rate (75-100 percent) of phenolic oxidation.